🔢
P1155 is a low-severity diagnostic code. Reading freeze-frame data and any paired codes is the fastest way to narrow it down. See top-rated scanners on Amazon ↗
These are statistical causes across ALL vehicles, your exact car may rank differently
The ranking changes by year, make, model, and mileage. Get a probability ranking built specifically for your vehicle.
🔎 Get the ranking for my exact car, $5.99 →
🎯 Top Causes & Probability
65%
#1 - Most Likely
Failed O2 Sensor Heater Element
Internal heater filament has gone open. Standard wear-out failure above 100k miles.
🔨 Part
$50-$200
👨🔧 Labor
$60-$160
⚡ DIY Difficulty
Easy
22%
#2 - Check First
Blown O2 Heater Fuse / Relay
Often a shared fuse - check before pulling the sensor.
🔨 Part
$5-$25
👨🔧 Labor
$40-$100
⚡ DIY Difficulty
Easy
12%
#3 - Less Common
Wiring or Connector Damage
Power or ground wire chafed against the exhaust pipe.
🔨 Part
$5-$50
👨🔧 Labor
$60-$160
⚡ DIY Difficulty
Medium
🚗 Most Affected Vehicles
🚫 Is It Safe to Drive?
Yes - normal driving is unaffected. The car may run slightly rich at cold start.
🔧 Step-by-Step Diagnosis
- Check the shared O2 heater fuse - One blown fuse can knock out heaters on multiple sensors.
- Measure heater resistance on B2S1 - Across the heater pins, 3-15 ohms when cold. Open = bad heater.
- Verify 12V supply at the connector - Backprobe with key on. No voltage means fuse, relay, or wiring.
- Inspect the sensor harness - Heat-damaged insulation along the exhaust pipe is the second most common cause.
- Replace the upstream O2 sensor - Sensor and heater are one assembly. Apply anti-seize on the threads.
❓ Frequently Asked Questions
Is P1155 dangerous to ignore?
No - it is a heater code, not a fueling code. Cat damage risk is low.
Will it pass inspection?
In states with OBD-II testing, the MIL itself is a fail.
How long do O2 heaters last?
Usually 100k-150k miles. Less in salt-belt states.
Can I just replace the fuse?
If the fuse blew due to a short, the new one will blow too. Diagnose first.
What is the difference between P1135 and P1155?
P1135 is Bank 1, P1155 is Bank 2 - same fault, opposite side of the engine.